$
[ Æ X Ø p-GaNù p § T Ó Þ X ¢ w Iy ¢ Y V Ët LED8 ý V R ËX ê s õ m Í ¤V R Ëç g Ë
®
£ . > £ · T - > Z 9 ∗
· ¡ ¤ @ / < Æ § / B N õ @ / < Æ èF / B N < ÆÂ Ò, èF > hµ 1 Ï ½ ¨G ' p' , · ¡ ¤ 561-756 (2005¸ 7 Z 4 11{ 9 ~ Ã Î6 £ §. 2005¸ 7 Z 4 25{ 9 þ j7 á x : r ~ Ã Î6 £ §)
InGaN/GaN × æ ª Ä ºÓ ü t ½ ¨ ¸ (MQW)\ ¦ Ö ¸$ í 8 £ x Ü ¼ Ð H ' õ AÒ o µ 1 ÏF g s ¸× ¼ (LED)_ ? /Â Ò ª
´ òÖ ¦` ¦ 7 £ x r v l 0 AK $ : r p-GaN` ¦ ¸{ 9 % i . \ x ~ Ã Ì} É r s # Q l ó ø Í 0 A\ Ä »l F K5 Å q o
<
Æl © 7 £ x à ÌZ O (MOCVD) Z O Ü ¼ Ð $ í © % i . 920
◦C \ " f 1060
◦C_ # 3 0 A\ " f p-GaN_ $ í © : r ¸
\
É r Cp
2Mg_ Ä »| ¾ Ó` ¦ þ j& h o % i ¦, ¦ : r (1020
◦C) \ " f þ j& h o ) a p-GaN õ q § # $ : r (960
◦
C) \ " f þ j& h o ) a p-GaN \ " f 8 ¾ Ó © ) a l ¸ ¸\ ¦ % 3 ` ¦ Ã º e % 3 . p-GaN_ $ í © : r ¸ LED
è : £ ¤$ í \ p u H % ò ¾ Ó` ¦ q § l 0 A # ¦ : r p-GaN (1020
◦C) õ $ : r p-GaN (960
◦C)` ¦ s 6 x ô
Ç 2> h_ LED\ ¦ ] j % i . ¦ : r p-GaN` ¦ & h 6 xô Ç LEDü < q § # $ : r p-GaN` ¦ & h 6 xô Ç LED
± ú
É r 1 l x · ú x 9 2C | ¾ Ó Z } É r > µ 1 ÏF g (EL) [ jl \ ¦ ? /% 3 . $ : r p-GaN` ¦ s 6 x # ] j ô Ç LED_ Z } É r EL [ jl _ " é ¶ É r p-GaN 8 £ x_ l ¸ ¸ 7 £ x \ É r À ÓÅ Ò{ 9 _ ¾ Ó © õ p-GaN 8 £ x
A \ > r F H MQW s ~ Ã Î H \ P & h \ P o_ y è\ _ # õ & h Ü ¼ Ð LED_ ª ´ òÖ ¦ s 7 £ x l
M :ë H כ Ü ¼ Ð ó ø Íé ß ) a .
PACS numbers: 61.72.Vv, 78.67.De, 85.60.Jb
Keywords: Ä »l F K5 Å q o < Æl © 7 £ x Ã Ì (MOCVD), $ : r p-GaN, InGaN/GaN, MQW, µ 1 ÏF g s ¸× ¼(LED)
I. " e  ] Ø
GaN, AlN, InN\ ¦ l ì ø ÍÜ ¼ Ð H 37 á ¤ | 9 oÓ ü tì ø Í ¸^ H V ,
É r F K t @ /; ¤ õ Z } É r breakdown field x 9 \ P ¸ ¸, Õ ª o
¦ radiation hardness 1 p x_ Ä ºÃ ºô Ç Ó ü t o & h $ í | 9 õ
¦ : r \ " f_ o < Æ& h î ß & ñ $ í ` ¦ t ¦ e . ÷ rë ß m
, s [ þ t | 9 oÓ ü tì ø Í ¸^ H Ö ¦ ¦6 x ^ \ ¦ s À Ò# Q ¸$ í
#
3 0 A\ " f f ] X ;s + þ A ì ø Í ¸^ _ : £ ¤$ í ` ¦ ? /l M :ë H \
;
¤V , É r \ -t % ò % i \ " f F g ´ òÖ ¦ s Ä ºÃ ºô Ç F g è \ _ 6
£
x6 x s 0 p x H © & h ¸ t ¦ e [1–3]. s [ þ t | 9
oÓ ü tì ø Í ¸^ \ ¦ s 6 x # s p ' õ AÒ o, 0 l qÒ o x 9 Ñ þ Ò o µ 1 ÏF g s
¸× ¼ (light emitting diode: LED) © 6 x o÷ &% 3 ¦, l
> r_ n t _ O q n ¸n Û ¼ß ¼ (DVD) $ © 6 x| ¾ Ó (4.7 Gb)` ¦ 5 C s © 7 £ x r [ j@ / DVD BlueRay (27 Gb)\
»
1 ÑF ½ + É pick-up 6 x 405 nm Ò o Y Us $ s ¸× ¼ > h µ
1 Ï ' × æ s . & ³F t 37 á ¤ | 9 oÓ ü t ì ø Í ¸^ \ ¦ s 6 x
#
¦ : r · ¦Ø ¦§ 4 è , ü @ Ø ¦ l , LED, Õ ªo ¦ Y
Us $ s ¸× ¼_ ½ ¨\ ´ ú § É r ' a d õ ¸§ 4 s | 9 × æ ÷ &
¦ e Ü ¼ , f t ¸ K K ½ + É Y > t H ë H ] j[ þ t s
z e .
∗
E-mail: [email protected];
Tel: 063-270-2292, Fax: 063-270-2305
InGaN/GaN × æ ª Ä ºÓ ü t ½ ¨ ¸ (multi-quantum well:
MQW) H ' õ AÒ o-0 l qÒ o x 9 H ü @ % ò % i _ LED\ © V , o
6 x H ½ ¨ ¸s . Ä ºÃ ºô Ç : £ ¤$ í ` ¦ InGaN/GaN
× æ ª Ä ºÓ ü t ½ ¨ ¸\ ¦ % 3 l 0 AK " f H $ í © : r ¸ 500
◦C s
© { 9 M : ë H ] jr ÷ & H InGaN_ Z } É r 6 fµ 1 Ï$ í ` ¦ ¦ 9K
ë ß ô Ç . t ë ß $ í © : r ¸ ± ú ` ¦ â Ä º 57 á ¤_ / B N/ å L" é ¶
¸m _ cracking efficiency y è H ë H ] j& h s µ 1 Ï Ò q
tô Ç H כ ¸ ¦ 9K ë ß ô Ç . " f ¦¾ ¡ §0 A InGaN
ª Ä ºÓ ü t` ¦ $ í © ½ + É M : H s Qô Ç ¿ º t ½ Ó` ¦ ¦ 9
#
750
◦C H % _ $ í © : r ¸\ ¦ s 6 xô Ç . t ë ß MQW
\
s # Q Ð + ' $ í © ÷ & H p-GaN 8 £ x É r a % ~ É r & ñ $ í
`
¦ % 3 l 0 AK 1000
◦C s © _ ¦ : r \ " f $ í © H X <, s
Z } É r $ í © : r ¸ M :ë H \ Â Ò\ $ í © ) a MQW ½ ¨ ¸_
& ñ | 9 s b # Qt H ë H ] j µ 1 ÏÒ q tô Ç . " f, p-GaN 8 £ x _
$ í © : r ¸\ ¦ ± ú Æ Ò Ð Ä ºÃ ºô Ç & ñ | 9 _ MQW` ¦
%
3 ` ¦ Ã º e # Q ? /Â Ò ª ´ òÖ ¦ s 7 £ x ½ + É כ Ü ¼ Ð \ V © ) a .
t ë ß p-GaN_ & h & ñ $ í © : r ¸ ∼ 1050
◦C Ð ± ú É r
: r ¸\ " f p-GaN` ¦ $ í © ½ + É â Ä º p-GaN_ & ñ | 9 s t
H é ß & h s e [4–6].
: r 7 Hë H \ " f H 960
◦C \ " f $ í © ô Ç $ : r p-GaN s 1020
◦
C \ " f $ í © ô Ç ¦ : r p-GaN Ð l ¸ ¸ 7 £ x H
כ
` ¦ S X % i . ¢ ¸ô Ç, $ : r p-GaN` ¦ s 6 x # ] j ô Ç
-164-
S X
½ + É Ã º e % 3 . s Qô Ç õ H $ : r p-GaN 8 £ x_ l
¸ ¸ 7 £ x \ É r À ÓÅ Ò{ 9 _ ¾ Ó © õ © @ /& h Ü ¼ Ð ± ú
É r p-GaN_ $ í © : r ¸ Ð # InGaN/GaN MQW ½ ¨
¸_ & ñ $ í s ¾ Ó © ÷ &# Q õ & h Ü ¼ Ð LED è _ ª
´
òÖ ¦ s 7 £ x l M :ë H כ Ü ¼ Ð « Ñ ) a .
II. ÷ m Ç ] M ö
$ í
© : r ¸\ ¦ ² ú o ô Ç p-GaN \ x ~ Ã Ì} x 9 ' õ AÒ o LED
½
¨ ¸ H (0001) s # Q l ó ø Í 0 A\ Ã ºf + þ A Ä »l F K5 Å q
o < Æl © 7 £ x Ã Ì (metalorganic chemical vapor deposition:
MOCVD) [ O q \ ¦ s 6 x # $ í © % i . Ga, In, Mg, x 9 N_ ½ ¨^ H y y à Ôo B j 9 ° ú µ ¢ § (TMGa), à Ôo B j 9
´
o u (TMIn), q Û ¼ s 9 þ t ÐK $ n \ u ´ Õ ªW 1¸ o u (Cp
2Mg) x 9
¸m \ ¦ 6 x % i . \ x ~ Ã Ì} $ í © \ s
#
Q l ó ø Í 0 A\ > r F ½ + Ét ¸Ø Ô H í ß oÓ ü t õ Ô ¦í HÓ ü t` ¦ \ P & h Ü
¼ Ð ] j l 0 A # l ó ø Í` ¦ 1100
◦C_ ¦ : r \ " f à º ì r ç
ß Ä »t r Ê ê, $ : r ! Q( 8 £ x 0 A\ 1045
◦C \ " f ¸i ç t
· ú § É r 1.2 µm ¿ ºa _ GaN \ x 8 £ x` ¦ $ í © % i .
Fig. 1. Schematic layer structure of p-GaN and In- GaN/GaN MQW LED.
í ¸ l 0 A # ¸i t · ¿ ºa _
GaN 0 A\ : r ¸ x 9 Cp
2Mg_ Ä »| ¾ Ó` ¦ or v " f Fig.
1(a)_ ½ ¨ ¸ü < ° ú s p-GaN` ¦ $ í © % i . s M : Cp
2Mg_ Ä
»| ¾ Ó É r 300 sccm \ " f 600 sccm_ # 3 0 A\ " f, $ í © : r ¸ H 920
◦C \ " f 1060
◦C_ # 3 0 A\ " f or v " f þ j& h _ $ í
© ¸| ` ¦ ¹ 1 Ô ¤ . 6 £ § Ü ¼ Ð, $ : r \ " f þ j& h o ) a p-GaN õ
¦ : r \ " f þ j& h o ) a p-GaN` ¦ s 6 x # ¿ º> h_ ' õ AÒ o LED ½ ¨ ¸\ ¦ $ í © % i . LED ½ ¨ ¸ H EL : £ ¤$ í q §\ ¦ 0 A # 0 p xô Ç ç ß é ß > [ O > % i Ü ¼ 9, n-GaNõ p-GaN
s \ µ 1 ÏF g8 £ x Ü ¼ Ð 5 Å Òl In
0.25Ga
0.75N/GaN MQW s
¶
ú { 9 ) a ½ ¨ ¸s (Fig. 1(b) Ã Ð ¸). # l " f InGaN well É r 750
◦C \ " f 2.5 nm_ ¿ ºa Ð $ í © % i ¦ GaN barrier H 850
◦C \ " f 14 nm_ ¿ ºa Ð $ í © % i .
$ í
© ô Ç r ¼ # \ @ / # s 1 l x ¸ü < H o # Q 0 l x ¸\ ¦
·
ú ? /l 0 AK Hall ´ òõ 8 £ ¤& ñ ` ¦ z ´r % i ¦, F g: £ ¤$ í ` ¦
¨ î
l 0 AK " f © : r photoluminescence (PL)` ¦ 8 £ ¤& ñ
Fig. 2. Room temperature PL spectra for p-GaN with different growth temperature. Inset plots PL intensity.
Fig. 3. Cp
2Mg flow rate dependence of PL intensity for
p-GaN with different growth temperature.
Fig. 4. Cp
2Mg flow rate dependence of electrical char- acteristics for p-GaN prepared at low and high growth temperature.
% i . LED_ ½ ¨1 l x: £ ¤$ í ` ¦ ¨ î l 0 AK " f EL x 9 À
Ó- · ú (I-V) : £ ¤$ í ` ¦ 8 £ ¤& ñ % i .
III. + s ÇÊ Ý õ m Í À X Ø8 ý
Fig. 2 H " f Ð É r : r ¸\ " f $ í © ô Ç p-GaN r ¼ # _
© : r PL Û ¼& 7 à Ô! 3 ` ¦ Ð# Å Ò ¦ e . 380 ∼ 400 nm H
%
\ " f Ðs H PL É r native donor | 9 è/ B N/ B N (V
N) õ Mg_ \ -t Y U6 \ ç ß ;s \ l H donor-acceptor pair (DAP) F ½ + ËÜ ¼ Ð · ú 94 R e . Õ ªa Ë >\ " fü < ° ú s PL_ [ jl H $ í © : r ¸ 7 £ x < Ê\ ° ú s 7 £ x H
כ
` ¦ · ú Ã º e . s õ H ¦ : r \ " f $ í © ô Ç p-GaN_ F
g < Æ& h & ñ $ í s $ : r \ " f $ í © ô Ç p-GaN Ð Ä ºÃ º
H כ ` ¦ Ð# Å Ò H כ s . Fig. 3 É r " f Ð É r : r ¸\ " f
$ í
© ô Ç [ j > h_ r ¼ # \ @ / # Cp
2Mg Ä »| ¾ Ó o\ É r PL_ µ 1 ÏF g [ jl \ ¦ Ð# Å Ò ¦ e . 400 ∼ 600 sccm_ # 3 0 A\ " f Cp
2Mg_ Ä »| ¾ Ós o 8 ¸ : r ¸ 7 £ x ½ + ÉÃ º 2
¤ PL [ jl 7 £ x H â ¾ Ó É r t · ú §6 £ §` ¦ · ú Ã º e
. 1000
◦C s © _ : r ¸\ " f $ í © ô Ç p-GaN ~ Ã Ì} _ â Ä º Cp
2Mg Ä »| ¾ Ós 7 £ x ½ + ÉÃ º2 ¤ PL [ jl y è H ¸_ þ v` ¦
Ðs H X <, Õ ª s Ä » H Mg ¸i ç 0 l x ¸ 7 £ x ½ + ÉÃ º2 ¤ auto- compensation [7] s 7 £ x l M :ë H כ Ü ¼ Ð « Ñ ) a .
auto-compensation É r native donor | 9 è/ B N/ B N (V
N) < Ê
É r | 9 è/ B N/ B N õ Mg_ ½ + Ë^ (Mg-V
N) " é ¶ s ¦ · ú
94 R e [7]. 960
◦C \ " f $ í © ô Ç p-GaN r ¼ # _ â Ä º\
H Cp
2Mg Ä »| ¾ Ós 7 £ x 8 ¸ PL [ jl H ß ¼> o t
· ú § ¤ H X < Õ ª " é ¶ ` ¦ ½ ©" î l 0 Aô Ç ½ ¨ ' × æ \ e
.
Fig. 4 H ¦ : r p-GaN (1020
◦C) õ $ : r p-GaN (960
◦
C) \ @ /K " f Cp
2Mg Ä »| ¾ Ó_ o\ H o # Q s 1 l x ¸ ü
< H o # Q 0 l x ¸_ Y L (7 £ ¤, l ¸ ¸/é ß 0 A | ¾ Ó)s
Fig. 5. In-situ reflectance measured for the blue LED structure
o H כ ` ¦ Ð# Å Ò ¦ e . Cp
2Mg_ Ä »| ¾ Ós 500 sccm s
{ 9 M :, F g < Æ& h : £ ¤$ í \ " fü < H ì ø Í@ / Ð $ : r \ " f $ í © ô
Ç p-GaN r ¼ # _ l & h : £ ¤$ í s Ð Ä ºÃ º H כ É r Å
Ò3 l q½ + É ë ß . Cp
2Mg_ Ä »| ¾ Ós 500 sccm{ 9 M : ¿ º r ¼ #
¸¿ º © Z } É r l ¸ ¸\ ¦ Ð% i ¦, Õ ª ° ú כ\ e # Q" f $
: r p-GaN s ¦ : r p-GaN Ð ¸F K 8 Z } É r à ºu \ ¦ l 2 ¤
H כ ` ¦ · ú Ã º e . s õ H $ : r p-GaN_ $ í © ¸
|
` ¦ & ñ x 9 > ¸] X Ù ¼ Ð+ ¦ : r p-GaN Ð Ä ºÃ ºô Ç l
& h : £ ¤$ í ` ¦ % 3 ` ¦ Ã º e H כ ` ¦ _ p ô Ç . ¢ ¸ô Ç, Fig.
2 ü < Fig. 3Ü ¼ ÐÂ Ò' F g < Æ& h : £ ¤$ í É r ¦ : r p-GaN s Ð Ä
ºÃ ºô Ç כ Ü ¼ Ð z ¤t ë ß , l & h : £ ¤$ í É r $ : r p-GaN s
Ð Ä ºÃ ºô Ç õ H Ð H כ ` ¦ r ¦ e .
p-GaN_ $ í © : r ¸ LED : £ ¤$ í \ p u H ´ òõ \ ¦ ¦¹ 1 Ï
l 0 A # , 960
◦C x 9 1020
◦C \ " f þ j& h o ) a ¸| Ü ¼ Ð
$ í
© ô Ç p-GaN` ¦ s 6 x # ' õ AÒ o LED ½ ¨ ¸\ ¦ ] j % i
. Fig. 5 H $ : r p-GaN` ¦ & h 6 xô Ç ' õ AÒ o LED\ ¦ $ í ©
H 1 l xî ß laser reflection` ¦ s 6 xô Ç in-situ monitoring 8 £ ¤& ñ
õ s . n-GaN_ ç ß [ O Á º] ( L : F M ¦ InGaN/GaN MQW_ well x 9 barrier Ì º§  s H כ Ü ¼ Ð Ð
$ í
© ) a LED_ y > s B Ä º Ä ºÃ º H כ ` ¦ · ú à º e
.
Table 1 É r $ : r p-GaN` ¦ s 6 x # ] j ô Ç ' õ AÒ o LED
½
¨ ¸\ @ / # 20 mA_ { 9 & ñ À Ó\ " f 8 £ ¤& ñ ô Ç · ú (V
f)
Table 1. I-V and EL characteristics at 20 mA forward current for the LEDs fabricated using low (1020
◦C) and high (960
◦C) p-GaN growth temperature
EL
T
Gof p-GaN Wavelength Intensity FWHM V
f(V) (nm) (a. u.) (meV)
960
◦C 475 11900 156 4.3
1020
◦C 483 6400 150 4.7
6 xô Ç LED Ð Ä ºÃ ºô Ç è $ í 0 p x` ¦ f ` ¦ · ú à º e
. $ , $ : r p-GaN` ¦ 6 xô Ç LED_ forward voltage (V
f@20mA) 8 ± ú É r X < s õ H Fig. 4 \ Ð l
& h : £ ¤$ í 8 £ ¤& ñ õ ü < ¸ ú { 9 u H כ s . ¢ ¸ô Ç, $ : r p-GaN` ¦ 6 xô Ç LED_ EL y © ¸ 2C Z } É r X <, Õ ª s
Ä » H $ : r p-GaN s InGaN/GaN MQW ½ ¨ ¸_ \ P & h
< H © ` ¦ ´ òõ & h Ü ¼ Ð } Å Ò% 3 l M :ë H כ Ü ¼ Ð ó ø Íé ß ) a
. 7 £ ¤, p-GaN_ $ í © : r ¸ Z }` ¦ Ã º2 ¤ p-GaN Ð 200
◦
C s © ± ú É r : r ¸\ " f $ í © ) a MQW ½ ¨ ¸ ¦ : r \ ¸ Ø
¦ ÷ &# Q p-GaN` ¦ $ í © H 1 l xî ß & ñ | 9 s \ P o÷ & ¦ ? / Â
Ò ª ´ òÖ ¦ É r y è > ) a .
þ
j H \ Wuü < Õ ª ½ ¨ [ þ t [4] É r 800
◦C_ $ : r p-GaN
`
¦ s 6 x # ] j ô Ç LED_ Ø ¦§ 4 s 1000
◦C_ ¦ : r p- GaN` ¦ 6 xô Ç כ Ð 2C & ñ ¸ 7 £ x ÷ &% 3 ¦ µ 1 ϳ ð
%
i . { 9 ì ø Í& h Ü ¼ Ð p-GaN` ¦ $ í © ½ + É M : Cp
2Mg_ Ä »| ¾ Ós B
Ä º ß ¼ 900
◦C s _ $ : r \ " f $ í © ³ ð s B
Ä º } 9 # Qt > ) a . Õ ª[ þ t É r LED Ø ¦§ 4 7 £ x _ " é ¶ ` ¦ 800
◦C_ $ : r \ " f { 9 Â Ò Q 2 ; ³ ð ` ¦ ° ú ¸2 ¤ $ í © ô Ç p- GaN \ _ K F g Æ ÒØ ¦ ´ òÖ ¦ (photon extraction efficiency) s 7
£
x ÷ &% 3 l M :ë H s ¦ µ 1 ß+ À I [4]. : r ½ ¨\ " f H ³ ð
} 9 l _ s \ É r F g Æ ÒØ ¦ ´ òÖ ¦_ o\ ¦ ¦¹ 1 Ï l 0 A # $ : r x 9 ¦ : r p-GaN \ x ~ à Ì} õ $ : r x 9 ¦ : r p-GaN` ¦ top layer Ð s 6 xô Ç ' õ AÒ o LED_ ³ ð + þ A © ` ¦ Nomarski F g < Æ & ³p â Ü ¼ Ð ' a¹ 1 Ï % i . Õ ª õ " f Ð
É
r : r ¸\ " f $ í © ô Ç p-GaN \ x ~ Ã Ì} s \ " f H Ó ü t : r ' õ
AÒ o LED r ¼ # \ " f_ p-GaN_ $ í © : r ¸\ É r ³ ð morphology _ s \ O 6 £ §` ¦ S X % i . " f,
: r z ´+ « > õ \ " f Ð 2C | ¾ Ó 7 £ x ô Ç EL y © ¸ H F g Æ Ò Ø
¦ ´ òÖ ¦_ 7 £ x Ð H [ O " î l j Ë µ[ þ t ¦ ? /Â Ò ª ´ òÖ ¦_ 7 £ x
M :ë H כ Ü ¼ Ð b # Q .
IV. + s Ç Â ] Ø
: r z ´+ « >\ " f H LED_ ? /Â Ò ª ´ òÖ ¦` ¦ 7 £ x r v l 0 AK $ : r p-GaN` ¦ ¸{ 9 % i . $ p-GaN_ $ í ©
: r ¸\ É r Cp
2Mg_ Ä »| ¾ Ó` ¦ þ j& h o % i Ü ¼ 9, ¦ : r (1020
◦C) \ " f þ j& h o ) a p-GaN õ q § # $ : r (960
◦
C) \ " f
`
¦ Ã º e % 3 . 6 £ § Ü ¼ Ð, p-GaN_ $ í © : r ¸ LED è
: £ ¤$ í \ p u H % ò ¾ Ó` ¦ q § l 0 A # ¦ : r p-GaN õ
$ : r p-GaN` ¦ s 6 xô Ç 2> h_ InGaN/GaN MQW LED\ ¦ ] j % i . ¦ : r p-GaN` ¦ & h 6 xô Ç LEDü < q §
# $ : r p-GaN` ¦ & h 6 xô Ç LED ± ú É r 1 l x · ú x 9 2 C | ¾ Ó Z } É r EL [ jl \ ¦ ? /% 3 . s Qô Ç õ H
$
: r p-GaN 8 £ x_ l ¸ ¸ 7 £ x \ É r À ÓÅ Ò{ 9 _
¾ Ó © õ © @ /& h Ü ¼ Ð ± ú É r p-GaN_ $ í © : r ¸ Ð # InGaN/GaN MQW ½ ¨ ¸_ & ñ $ í s ¾ Ó © ÷ &# Q õ & h Ü
¼ Ð LED è _ ª ´ òÖ ¦ s 7 £ x l M :ë H כ Ü ¼ Ð
« Ñ ) a .
P c
p 8 ý ò k >
s
7 Hë H É r 2004¸ ¸ ô Dz D G < ÆÕ ü t < É ª F é ß _ t " é ¶ \ _
#
½ ¨÷ &% 3 6 £ §. (KRF-2004-003-D00143)
Y c
p w à U Ø ô
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Growth and Characterization of a High-Brightness Blue LED Using p-GaN Grown at a Low Temperature
Jin-Woo Ju and In-Hwan Lee
∗School of Advanced Materials Engineering and Research Center for Advanced Materials Development, Engineering College, Chonbuk National University, Chonju 561-756
(Received 11 July 2005, in final form 25 July 2005)
The effect of the growth temperature of the p-GaN top layer on the characteristics of blue light- emitting diodes (LEDs) was investigated. The LED structures were grown on c-plane sapphire substrates by using metalorganic chemical-vapor deposition. In order to achieve better LED perfor- mance, we optimized the product of the mobility and the concentration for p-GaN layers prepared at different temperatures and Cp
2Mg flow rates. After the optimization, two In
0.25Ga
0.75N/GaN multi-quantum well (MQW) LED structures with different p-GaN growth temperature were tested.
A times higher electroluminescence (EL) intensity was observed for the LED structure with grown at a low temperature of 960
◦C than was observed for the p-GaN layer grown at a higher tempera- ture of 1020
◦C. This result can be explained by an enhancement in the internal quantum efficiency resulting from the better interface quality of the underlying InGaN/GaN MQW active layers.
PACS numbers: 61.72.Vv, 78.67.De, 85.60.Jb
Keywords: MOCVD, Low temperature p-GaN, InGaN/GaN, MQW, Light emitting diode
∗
